92 
BRITISH ENTOMOSTRACA. 
has only three articulations, all of nearly equal length. 
From the first and second a long filament is sent forth, 
and three others spring from the extremity of the third. 
These filaments are all beautifully plumose, and have a 
joint at about the middle of their length.* The sixth 
segment of the body has four projections issuing from it, 
the first being prolonged, and bent upwards. 
The male is much smaller than the female. The su- 
perior antennae are much larger, and spring from under 
the beak, instead of from the beak itself. The inferior 
extremities of the valves are more densely serrated than 
in the female. It is comparatively rarely to be met with. 
Hab . — In almost all pools, and ditches of standing 
water, round London, &c. ; common from April to 
^ J 11 T n 349, W. Thompson, Esq. 
2. Daphnia psittacea. Tab. IX. figs. 3, 4. 
Valves of shell, or carapace, oval, transparent, nearly 
colourless. The head is large, somewhat square-shaped, 
and the anterior part is beaked like the beak of a parrot. 
The superior antennae are short, but larger than in pre- 
ceding species, and rise from the under surface of the 
beak. The posterior angle of the shell terminates in a 
long, sharp point, which is closely serrated on both sides. 
The margins of the valves are also closely serrated over 
the greater part of their length, the serrse of dorsal margin 
extending to near the commencement of the head. The 
filaments of the antennae and abdominal lobe are finely 
plumose. The eye is large. 
This species bears considerable resemblance to the 
D . pulex, and at first sight may be easily confounded 
with it. Upon close examination, however, the form of 
the head, and the serrated dorsal margin, distinguish it 
* The number of the articulations, their relative size, and the number and 
distribution of the filaments of these antennae, are the same in all the species 
of the genus Daphnia. 
